I. Field of the Invention
The current invention relates to mobility within a telecommunications system. More particularly, the present invention relates to a method and apparatus for transparently relocating an anchor point within the serving network of a wireless telecommunications system from one location to another.
II. Description of the Related Art
The use of a decentralized serving network for use in a wireless telecommunications system is disclosed in U.S. patent application. Ser. No. 09/158,047, entitled xe2x80x9cDISTRIBUTED INFRASTRUCTURE FOR WIRELESS DATA COMMUNICATIONSxe2x80x9d, applied for by the applicant of the present invention now U.S. Pat. No. 6,215,779, and incorporated by reference herein. The above application discusses a telecommunications decentralized serving network in which, rather than there being a single point of control, there are multiple control points distributed throughout the serving network of the telecommunications system.
The Internet Engineering Task Force (IETF) is the standards body that creates the majority of standards related to the Internet Protocol (IP). Many of the standards created by the IETF are called RFCs. RFC is shorthand for xe2x80x98Request For Comments.xe2x80x99
Open Shortest Path First (OSPF) was standardized by the IETF to address, in part, the routing of packets in a network in which one or more of the routers experiences a failure, thus enhancing the reliability of a network. OSPF was designed in such a way that, of all the routers which are working at any given moment, the shortest path is taken from node A to node B. Additionally, OSPF was designed such that, if multiple equivalent routes exist from node A to node B, any one of the equivalent routes can be selected. With OSPF in place, a network with redundant routes can perform load balancing on the routers. OSPF is available on many makes and models of routers, and is described in IETF RFC 2328, incorporated by reference herein.
Mobile IP is present in many IETF standards to make it possible for a device, containing an IP address, to travel through a network (or networks). The standard, RFC 2002, xe2x80x98IP Mobility Support,xe2x80x99 incorporated by reference herein, addresses the problem of IP Mobility, and uses a solution termed xe2x80x98Mobile IP.xe2x80x99 Several other Mobile IP related standards also exist, such as RFCs 2006, 2041, 2290, 2344, and 2356, each of which is incorporated by reference herein. Local Area Network (LAN) system administrators that want to support mobility are guided by the IETF standards to use Mobile IP. Mobile IP provides support not only for mobility within a LAN, but also for mobility within a Wide Area Network (WAN).
In a decentralized telecommunications network, the service devices chosen are widely available off-the-shelf units that use open standards for their interfaces rather than proprietary protocols that are limited to a single supplier. Many, if not all, of the service devices are designed to communicate with a single anchor point for each active session. Meaning, such off-the-shelf devices, and the protocols they incorporate, are not designed to begin a session with one device and ends the same session with a different device. This restriction can lead to non-optimized routing for individual sessions. Such non-optimized routing situations are illustrated in FIG. 8A and FIG. 8B. What is needed is a method by which a service device""s anchor point for an active session can be relocated without the need for specific anchor point relocation support in the service device. Specifically, such a method should be very efficient and robust, minimizing latency and bandwidth usage.
The present invention is a novel method and apparatus for providing transparent mobility of an entity within a serving network of a wireless telecommunications system. The invention provides for the transparent mobility of a data anchor point within a network, allowing the anchor point to move from one physical location of the network to another physical location of the network. The type of mobility is termed xe2x80x98transparentxe2x80x99 because the peer entity communicating with the anchor point doesn""t receive a message indicating that the anchor point has moved, nor is the peer entity required to perform any special functions to remain in communication with an anchor point that has moved from one location to another. In other words, the peer entity communicating with the data anchor point performs no differently in a session in which the anchor point remains fixed than it does in a session in which the anchor point changes physical locations.
The present invention is applicable to decentralized networks in which transparent mobility is desired. The present invention is particularly applicable on networks wherein it is desired that the mobility mechanism neither introduces latency nor decreases the available bandwidth of the network. Such networks include, but are not limited to, a CDMA wireless data network and a GSM wireless data network.
All embodiments of the present invention are novel methods and apparatus for handling mobility within a serving network of a wireless telecommunications system. The exemplary embodiment of the present invention has broader applicability, in that it provides a novel method for handling mobility in all types of networks, including corporate and government networks. Other mobility models can require a centralized network to manage anchor point mobility. Additionally, other mobility models can use of a significant amount of available bandwidth and can significantly increase latency. The present invention neither has deleterious latency nor bandwidth effects. Additionally, the present invention utilizes standard protocols that are widely available from a plurality of equipment manufacturers on a variety of platforms. Thus, the present invention provides a very cost-effective model for network providers that desire to support transparent mobility within their network.
The exemplary embodiment of the present invention uses OSPF to achieve transparent anchor point mobility. Mobile IP is used in an alternative embodiment of the present invention to provide transparent anchor point mobility in the serving network of a wireless telecommunications system. OSPF is used in the exemplary embodiment of the present invention because the use of OSPF does not introduce the tunneling overhead that is introduced Mobile IP, and OSPF does not introduce the latency that can be caused by the indirect routing common in Mobile IP.